Trends in Logic XI. Advances in Philosophical Logic, Bochum, June 2012, as chair of the program committee, with Roberto Ciuni and Caroline Willkommen, supported by GAP, DVMLG and Alexander von Humboldt Foundation.

Trends in Logic IV. Towards Mathematical Philosophy, Torun, September 2006, as cochair of the program committee, supported by Volkswagen Foundation, Hannover.

Advances in Modal Logic 2004 (AiML '04), Manchester (UK), September 2004, as a founding member of the initiative "Advances in Modal Logic" and co-chair of the program committee, supported by European Union COST Action 274, British Logic Colloquium, Murdoch University (Perth), University of Manchester.

75 Years of Predicate Logic FOL 75, Berlin (Germany), September 2003, as head of the program committee and member of the core group of organizers, supported by DFG.

Advances in Modal Logic 2002 (AiML '02), Toulouse (France), September 2002, as a founding member of the initiative "Advances in Modal Logic"and member of the program committee, supported by Paul Sabatier University.

3rd Conference on Logic and Logical Philosophy of the Polish Association for Logic and Philosophy of Science (PTL) and Gesellschaft für Analytische Philosophie (GAP), Dresden (Germany), March 2001, organized with M. Urchs, supported by GAP, the Saxon Ministry for Science and Art and Dresden University of Technology.

Advances in Modal Logic-International Conference on Temporal Logic 2000 (AiML-ICTL 2000), Leipzig (Germany), October 2000, as a founding member of the initiative "Advances in Modal Logic"and member of the program committee, supported by the German Research Council (DFG).

Workshop The Legacy of the Lvov-Warsaw School, as part of the conference Argument und Analyse, Bielefeld (Germany), September 2000, supported by DAAD and GAP.

Workshop The Legacy of the Lvov-Warsaw School, as part of the conference Argument und Analyse, Bielefeld (Germany), September 2000, supported by DAAD and GAP.

Workshop Nichtklassische Formen der Logik, Konstanz (Germany) October 1999, as part of the 18th Congress of the Allgemeine Gesellschaft für Philosophie in Deutschland (AGPD).

Advances in Modal Logic 1998 (AiML '98), Uppsala (Sweden), October 1998, as a founding member of the initiative "Advances in Modal Logic"and member of the program committee, supported by the Royal Academy of Sciences.

2nd Conference on Logic and Logical Philosophy of the Polish Association for Logic and Philosophy of Science (PTL) and Gesellschaft für Analytische Philosophie (GAP), Zagan (Poland), April 1998, organized with A. Wisniewski, M. Urchs and S. Gottwald, supported by GAP, Robert Bosch Foundation (Stuttgart) and the University of Zielona Gora (Poland).

Advances in Modal Logic 1996 (AiML '96), Berlin (Germany), October 1996, as a founding member of the initiative "Advances in Modal Logic"and member of the program committee, supported by Neurotec Hochtechnologie GmbH, European Network of Excellence in Computational Logic and Berliner Mathematische Gesellschaft.

Swedish-German Workshop on Belief Revision, Leipzig (Germany), May 1996, supported by Svenska Institutet and the Center for Advances Studies at the University of Leipzig.

1st Conference on Logic and Logical Philosophy of the Polish Association for Logic and Philosophy of Science (PTL) and Gesellschaft für Analytische Philosophie (GAP), Torun (Poland), September 1995, organized with M. Urchs, supported by GAP, German Academic Exchange Service DAAD and the University of Torun.

Workshop Modellierung epistemischer Operatoren, Saarbrücken (Germany), as part of
the conference "KI '94", September 1994, organized with A. Laux, supported by the German Research Center for Articial Intelligence (DFKI).

Workshop Negation as part of the conference Analyomen 2, Leipzig (Germany), September
1994, supported by Gesellschaft für Analytische Philosophie and the Center for Advances Studies at Leipzig University.